What it treats. Cryotherapy uses liquid nitrogen, colder than 300 degrees below zero Fahrenheit, to treat warts, precancerous actinic keratoses, seborrheic keratoses and other small growths.
- Freeze. A spray of liquid nitrogen is aimed at the growth for a few seconds. Ice forms inside the abnormal cells and breaks them apart, while the surrounding skin is spared.
- Thaw. The frozen spot turns white, then thaws over a minute or so. It stings during the freeze and thaw, then settles. Some lesions are frozen twice in the same visit.
- Blister and crust. Over the next day or two the area may swell or blister, then forms a crust. The crust separates on its own within one to two weeks.
- Heal. Fresh skin forms beneath the crust. The treated spot may be lighter or pinker for a while, and thicker growths sometimes need a second session.